1. Field of the Invention
The present invention relates to a multi-medium store-and-forward exchange apparatus for performing transfer, storage and conversion of various sorts of data and a method of controlling the apparatus, and more particularly, to a multi-medium store-and-forward exchange apparatus which is connected to a plurality of line networks so that the apparatus converts data received from communication terminals of one line network into data suitable for different line networks and sends the converted data to associated party terminals of the different line networks and a method of controlling the apparatus.
2. Description of the Related Art
A prior art store-and-forward exchange apparatus of the type referred to above has been connected to a single line exchange network so that the apparatus receives data from a terminal through the line exchange network and sends it to a party terminal through the same network.
There recently has been suggested a store-and-forward exchange apparatus connected to a plurality of line exchange networks of different types, including a voice line exchange network for transmitting voice signals, a picture line exchange network for transmitting picture data and a character line exchange network for transmitting character data.
The conventional store-and-forward exchange apparatus is basically designed so that the apparatus sends a voice signal received from a voice terminal (which generates the voice signal), to a party terminal through one of the lines connected to the voice line exchange network, sends a picture signal received from a picture terminal (which generates the picture signal), to a party terminal through one of the lines connected to the picture line exchange network, and sends a character signal received from a character terminal (which generates the character signal), to a party terminal through one of the lines connected to the character line exchange network. For this reason, when all the lines connected, e.g., to the picture line exchange network are in use but there is idle one of the lines connected, e.g., to the character line exchange network, the prior art store-and-forward exchange apparatus cannot transmit the data received through the picture line exchange network to the party terminal but must wait until one of the lines connected to the picture line exchange network becomes idle.
In order to remove the above disadvantage, it may be considered to determine the number of lines depending on the expected amount of the communication for each sort of media. Even in this case, however, when the amount of communication to line exchange network is unexpectedly increased, the transmission to terminals connected to that line exchange network is delayed and thus equal servicing to every terminal cannot be realized. For the purpose of overcoming this disadvantage, it may be considered to increase the number of lines connected to each of line exchange networks. This, however, involves another problem that the cost becomes high.